Preparation Of Coal-based Solid Amine Adsorbent And CO₂ Electric Swing Adsorption

Climate changing due to the large-scale emission of greenhouse gas has a huge impact on the global ecosystem.Carbon dioxide,one of the greenhouse gases,should be captured to stabilized its concentration in the atmosphere.Electric swing adsorption?ESA?based on solid amine adsorbents has the advantages of high energy efficiency,fast heating rate,simple equipment and good selectivity.Now,ESA has become a novel carbon dioxide capture technology.And porous carbon materials with rich porosity,excellent electrothermal performance and thermal stability are considered to be good candidate supporters for ESA.In this thesis,integrated coal-based microfiltration carbon membrane was prepared by using cheap coal as raw material combined with pore formers and binders,followed by extrusion molding and carbonization.The solid amine adsorbent was prepared by physical impregnation approach with carbon membrane as a conductive supporter and amines with different structures as adsorbents,the ESA module was constructed thereby.The micro structure and electrothermal properties of coal-based carbon membranes,the effects of organic amines with different structures on the CO₂ adsorption and the adsorption mechanism were studied in this paper.The main results are summarized as follows:?1?The carbon membrane has a flat surface,moderate porosity and excellent mechanical strength.It also can be rapidly heat up under an external voltage.Meanwhile,the surface temperature distribution of the carbon membrane is uniform during the process of heating and cooling,and no local supercooling or overheating zone is observed.Therefore,coal-based microfiltration carbon membrane should be a good conductive supporter for ESA?2?Propylene oxide?PO?or epichlorohydrin?ECH?were used to modify or crosslink diethylenetriamine?DETA?and tetraethylenepentamine?TEPA?respectively,in order to introduce alcoholic hydroxyl groups on the carbon chains to increase the molecular weight of amines and enhance intermolecular forces,thus the boiling points of the resulted organic amine increased.However,the increase in molecular weight will result in a decrease in active adsorption sites on a unit amine,which in turn lead to a slight decrease in CO₂ adsorption capacity for the first cycle,but a significant enhancement in cyclic performance.Among all the adsorbents,the amine crosslinked by ECH has the best cycle performance.After 10 cycles of CO₂/N₂ and CO₂/CH₄ separation tests at 30?and 101.325 kPa,DETA-c-ECH preserved adsorption capacity of 82.8%and 88.6%,while the adsorption capacities of TEPA-c-ECH can maintain at 90.4%and 84.8%.?3?Coal-based tubular carbon membranes impregnated with organic amine have a similar mechanism with fixed-bed adsorbents for CO₂ adsorption.However,the bed thickness is extremely small and the pressure drop has been reduced drastically,so the gas can quickly penetrate the tube wall.The pore size of the carbon membrane will be reduced after amine loading.And some of the pores may be blocked,thus the resistance for mass transfer of gas will be increased.At the same time,the relative weak chemical interaction between amine and CO₂can facilitate effective separation and rapid desorption of CO₂.